Patent Literature 1 describes an optical module including a lens array, a photoelectric conversion device, and an optical fiber. The photoelectric conversion device includes a semiconductor substrate, a plurality of light emitting elements mounted on the semiconductor substrate, and the same number of light receiving elements as the light emitting elements disposed on the semiconductor substrate. The lens array includes a first lens surface, a total reflection surface, a reflection and transmission layer, a second lens surface, and a third lens surface. The first lens surface receives light from the light emitting element. The total reflection surface totally reflects light from the first lens surface. The reflection and transmission layer reflects and transmits light from the total reflection surface. The second lens surface condenses light transmitted by the reflection and transmission layer on the optical fiber. The third lens surface condenses light reflected by the reflection and transmission layer on the light receiving element. The optical fibers, the first lens surfaces, the second lens surfaces, and the third lens surfaces are disposed in the same number as the light emitting elements and the light receiving elements. In compactation of the optical module, a large alignment error between the light emitting element of the photoelectric conversion device and the first lens surface of the lens array and/or a large alignment error between the light receiving element and the third lens surface of the lens array causes light deviated from an original optical path, called stray light, from light output from a certain light emitting element. The stray light enters a light receiving element adjacent to a light receiving element corresponding to the light emitting element, and deteriorates performance of the optical module. It is desirable to reduce an influence of such stray light on the light receiving element.    [Patent Literature 1] Japanese Unexamined Patent Publication No. 2011-133807